net/rxrpc/input.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* RxRPC packet reception
   3  *
   4  * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/net.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/errqueue.h>
  14 #include <linux/udp.h>
  15 #include <linux/in.h>
  16 #include <linux/in6.h>
  17 #include <linux/icmp.h>
  18 #include <linux/gfp.h>
  19 #include <net/sock.h>
  20 #include <net/af_rxrpc.h>
  21 #include <net/ip.h>
  22 #include <net/udp.h>
  23 #include <net/net_namespace.h>
  24 #include "ar-internal.h"
  25
  26 static void rxrpc_proto_abort(const char *why,
  27                               struct rxrpc_call *call, rxrpc_seq_t seq)
  28 {
  29         if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, -EBADMSG)) {
  30                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
  31                 rxrpc_queue_call(call);
  32         }
  33 }
  34
  35 /*
  36  * Do TCP-style congestion management [RFC 5681].
  37  */
  38 static void rxrpc_congestion_management(struct rxrpc_call *call,
  39                                         struct sk_buff *skb,
  40                                         struct rxrpc_ack_summary *summary,
  41                                         rxrpc_serial_t acked_serial)
  42 {
  43         enum rxrpc_congest_change change = rxrpc_cong_no_change;
  44         unsigned int cumulative_acks = call->cong_cumul_acks;
  45         unsigned int cwnd = call->cong_cwnd;
  46         bool resend = false;
  47
  48         summary->flight_size =
  49                 (call->tx_top - call->tx_hard_ack) - summary->nr_acks;
  50
  51         if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
  52                 summary->retrans_timeo = true;
  53                 call->cong_ssthresh = max_t(unsigned int,
  54                                             summary->flight_size / 2, 2);
  55                 cwnd = 1;
  56                 if (cwnd >= call->cong_ssthresh &&
  57                     call->cong_mode == RXRPC_CALL_SLOW_START) {
  58                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  59                         call->cong_tstamp = skb->tstamp;
  60                         cumulative_acks = 0;
  61                 }
  62         }
  63
  64         cumulative_acks += summary->nr_new_acks;
  65         cumulative_acks += summary->nr_rot_new_acks;
  66         if (cumulative_acks > 255)
  67                 cumulative_acks = 255;
  68
  69         summary->mode = call->cong_mode;
  70         summary->cwnd = call->cong_cwnd;
  71         summary->ssthresh = call->cong_ssthresh;
  72         summary->cumulative_acks = cumulative_acks;
  73         summary->dup_acks = call->cong_dup_acks;
  74
  75         switch (call->cong_mode) {
  76         case RXRPC_CALL_SLOW_START:
  77                 if (summary->nr_nacks > 0)
  78                         goto packet_loss_detected;
  79                 if (summary->cumulative_acks > 0)
  80                         cwnd += 1;
  81                 if (cwnd >= call->cong_ssthresh) {
  82                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  83                         call->cong_tstamp = skb->tstamp;
  84                 }
  85                 goto out;
  86
  87         case RXRPC_CALL_CONGEST_AVOIDANCE:
  88                 if (summary->nr_nacks > 0)
  89                         goto packet_loss_detected;
  90
  91                 /* We analyse the number of packets that get ACK'd per RTT
  92                  * period and increase the window if we managed to fill it.
  93                  */
  94                 if (call->peer->rtt_usage == 0)
  95                         goto out;
  96                 if (ktime_before(skb->tstamp,
  97                                  ktime_add_ns(call->cong_tstamp,
  98                                               call->peer->rtt)))
  99                         goto out_no_clear_ca;
 100                 change = rxrpc_cong_rtt_window_end;
 101                 call->cong_tstamp = skb->tstamp;
 102                 if (cumulative_acks >= cwnd)
 103                         cwnd++;
 104                 goto out;
 105
 106         case RXRPC_CALL_PACKET_LOSS:
 107                 if (summary->nr_nacks == 0)
 108                         goto resume_normality;
 109
 110                 if (summary->new_low_nack) {
 111                         change = rxrpc_cong_new_low_nack;
 112                         call->cong_dup_acks = 1;
 113                         if (call->cong_extra > 1)
 114                                 call->cong_extra = 1;
 115                         goto send_extra_data;
 116                 }
 117
 118                 call->cong_dup_acks++;
 119                 if (call->cong_dup_acks < 3)
 120                         goto send_extra_data;
 121
 122                 change = rxrpc_cong_begin_retransmission;
 123                 call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
 124                 call->cong_ssthresh = max_t(unsigned int,
 125                                             summary->flight_size / 2, 2);
 126                 cwnd = call->cong_ssthresh + 3;
 127                 call->cong_extra = 0;
 128                 call->cong_dup_acks = 0;
 129                 resend = true;
 130                 goto out;
 131
 132         case RXRPC_CALL_FAST_RETRANSMIT:
 133                 if (!summary->new_low_nack) {
 134                         if (summary->nr_new_acks == 0)
 135                                 cwnd += 1;
 136                         call->cong_dup_acks++;
 137                         if (call->cong_dup_acks == 2) {
 138                                 change = rxrpc_cong_retransmit_again;
 139                                 call->cong_dup_acks = 0;
 140                                 resend = true;
 141                         }
 142                 } else {
 143                         change = rxrpc_cong_progress;
 144                         cwnd = call->cong_ssthresh;
 145                         if (summary->nr_nacks == 0)
 146                                 goto resume_normality;
 147                 }
 148                 goto out;
 149
 150         default:
 151                 BUG();
 152                 goto out;
 153         }
 154
 155 resume_normality:
 156         change = rxrpc_cong_cleared_nacks;
 157         call->cong_dup_acks = 0;
 158         call->cong_extra = 0;
 159         call->cong_tstamp = skb->tstamp;
 160         if (cwnd < call->cong_ssthresh)
 161                 call->cong_mode = RXRPC_CALL_SLOW_START;
 162         else
 163                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 164 out:
 165         cumulative_acks = 0;
 166 out_no_clear_ca:
 167         if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
 168                 cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
 169         call->cong_cwnd = cwnd;
 170         call->cong_cumul_acks = cumulative_acks;
 171         trace_rxrpc_congest(call, summary, acked_serial, change);
 172         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 173                 rxrpc_queue_call(call);
 174         return;
 175
 176 packet_loss_detected:
 177         change = rxrpc_cong_saw_nack;
 178         call->cong_mode = RXRPC_CALL_PACKET_LOSS;
 179         call->cong_dup_acks = 0;
 180         goto send_extra_data;
 181
 182 send_extra_data:
 183         /* Send some previously unsent DATA if we have some to advance the ACK
 184          * state.
 185          */
 186         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 187             RXRPC_TX_ANNO_LAST ||
 188             summary->nr_acks != call->tx_top - call->tx_hard_ack) {
 189                 call->cong_extra++;
 190                 wake_up(&call->waitq);
 191         }
 192         goto out_no_clear_ca;
 193 }
 194
 195 /*
 196  * Ping the other end to fill our RTT cache and to retrieve the rwind
 197  * and MTU parameters.
 198  */
 199 static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb,
 200                             int skew)
 201 {
 202         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 203         ktime_t now = skb->tstamp;
 204
 205         if (call->peer->rtt_usage < 3 ||
 206             ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
 207                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 208                                   true, true,
 209                                   rxrpc_propose_ack_ping_for_params);
 210 }
 211
 212 /*
 213  * Apply a hard ACK by advancing the Tx window.
 214  */
 215 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
 216                                    struct rxrpc_ack_summary *summary)
 217 {
 218         struct sk_buff *skb, *list = NULL;
 219         bool rot_last = false;
 220         int ix;
 221         u8 annotation;
 222
 223         if (call->acks_lowest_nak == call->tx_hard_ack) {
 224                 call->acks_lowest_nak = to;
 225         } else if (before_eq(call->acks_lowest_nak, to)) {
 226                 summary->new_low_nack = true;
 227                 call->acks_lowest_nak = to;
 228         }
 229
 230         spin_lock(&call->lock);
 231
 232         while (before(call->tx_hard_ack, to)) {
 233                 call->tx_hard_ack++;
 234                 ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
 235                 skb = call->rxtx_buffer[ix];
 236                 annotation = call->rxtx_annotations[ix];
 237                 rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
 238                 call->rxtx_buffer[ix] = NULL;
 239                 call->rxtx_annotations[ix] = 0;
 240                 skb->next = list;
 241                 list = skb;
 242
 243                 if (annotation & RXRPC_TX_ANNO_LAST) {
 244                         set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 245                         rot_last = true;
 246                 }
 247                 if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
 248                         summary->nr_rot_new_acks++;
 249         }
 250
 251         spin_unlock(&call->lock);
 252
 253         trace_rxrpc_transmit(call, (rot_last ?
 254                                     rxrpc_transmit_rotate_last :
 255                                     rxrpc_transmit_rotate));
 256         wake_up(&call->waitq);
 257
 258         while (list) {
 259                 skb = list;
 260                 list = skb->next;
 261                 skb_mark_not_on_list(skb);
 262                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 263         }
 264
 265         return rot_last;
 266 }
 267
 268 /*
 269  * End the transmission phase of a call.
 270  *
 271  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 272  * or a final ACK packet.
 273  */
 274 static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 275                                const char *abort_why)
 276 {
 277         unsigned int state;
 278
 279         ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 280
 281         write_lock(&call->state_lock);
 282
 283         state = call->state;
 284         switch (state) {
 285         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 286         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 287                 if (reply_begun)
 288                         call->state = state = RXRPC_CALL_CLIENT_RECV_REPLY;
 289                 else
 290                         call->state = state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 291                 break;
 292
 293         case RXRPC_CALL_SERVER_AWAIT_ACK:
 294                 __rxrpc_call_completed(call);
 295                 rxrpc_notify_socket(call);
 296                 state = call->state;
 297                 break;
 298
 299         default:
 300                 goto bad_state;
 301         }
 302
 303         write_unlock(&call->state_lock);
 304         if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 305                 trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 306         else
 307                 trace_rxrpc_transmit(call, rxrpc_transmit_end);
 308         _leave(" = ok");
 309         return true;
 310
 311 bad_state:
 312         write_unlock(&call->state_lock);
 313         kdebug("end_tx %s", rxrpc_call_states[call->state]);
 314         rxrpc_proto_abort(abort_why, call, call->tx_top);
 315         return false;
 316 }
 317
 318 /*
 319  * Begin the reply reception phase of a call.
 320  */
 321 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 322 {
 323         struct rxrpc_ack_summary summary = { 0 };
 324         unsigned long now, timo;
 325         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 326
 327         if (call->ackr_reason) {
 328                 spin_lock_bh(&call->lock);
 329                 call->ackr_reason = 0;
 330                 spin_unlock_bh(&call->lock);
 331                 now = jiffies;
 332                 timo = now + MAX_JIFFY_OFFSET;
 333                 WRITE_ONCE(call->resend_at, timo);
 334                 WRITE_ONCE(call->ack_at, timo);
 335                 trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
 336         }
 337
 338         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 339                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 340                         rxrpc_proto_abort("TXL", call, top);
 341                         return false;
 342                 }
 343         }
 344         if (!rxrpc_end_tx_phase(call, true, "ETD"))
 345                 return false;
 346         call->tx_phase = false;
 347         return true;
 348 }
 349
 350 /*
 351  * Scan a jumbo packet to validate its structure and to work out how many
 352  * subpackets it contains.
 353  *
 354  * A jumbo packet is a collection of consecutive packets glued together with
 355  * little headers between that indicate how to change the initial header for
 356  * each subpacket.
 357  *
 358  * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 359  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 360  * size.
 361  */
 362 static bool rxrpc_validate_jumbo(struct sk_buff *skb)
 363 {
 364         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 365         unsigned int offset = sizeof(struct rxrpc_wire_header);
 366         unsigned int len = skb->len;
 367         int nr_jumbo = 1;
 368         u8 flags = sp->hdr.flags;
 369
 370         do {
 371                 nr_jumbo++;
 372                 if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 373                         goto protocol_error;
 374                 if (flags & RXRPC_LAST_PACKET)
 375                         goto protocol_error;
 376                 offset += RXRPC_JUMBO_DATALEN;
 377                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 378                         goto protocol_error;
 379                 offset += sizeof(struct rxrpc_jumbo_header);
 380         } while (flags & RXRPC_JUMBO_PACKET);
 381
 382         sp->nr_jumbo = nr_jumbo;
 383         return true;
 384
 385 protocol_error:
 386         return false;
 387 }
 388
 389 /*
 390  * Handle reception of a duplicate packet.
 391  *
 392  * We have to take care to avoid an attack here whereby we're given a series of
 393  * jumbograms, each with a sequence number one before the preceding one and
 394  * filled up to maximum UDP size.  If they never send us the first packet in
 395  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 396  * space until the call times out.
 397  *
 398  * We limit the space usage by only accepting three duplicate jumbo packets per
 399  * call.  After that, we tell the other side we're no longer accepting jumbos
 400  * (that information is encoded in the ACK packet).
 401  */
 402 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 403                                  u8 annotation, bool *_jumbo_bad)
 404 {
 405         /* Discard normal packets that are duplicates. */
 406         if (annotation == 0)
 407                 return;
 408
 409         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 410          * more partially duplicate jumbo packets, we refuse to take any more
 411          * jumbos for this call.
 412          */
 413         if (!*_jumbo_bad) {
 414                 call->nr_jumbo_bad++;
 415                 *_jumbo_bad = true;
 416         }
 417 }
 418
 419 /*
 420  * Process a DATA packet, adding the packet to the Rx ring.
 421  */
 422 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb,
 423                              u16 skew)
 424 {
 425         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 426         enum rxrpc_call_state state;
 427         unsigned int offset = sizeof(struct rxrpc_wire_header);
 428         unsigned int ix;
 429         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 430         rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
 431         bool immediate_ack = false, jumbo_bad = false, queued;
 432         u16 len;
 433         u8 ack = 0, flags, annotation = 0;
 434
 435         _enter("{%u,%u},{%u,%u}",
 436                call->rx_hard_ack, call->rx_top, skb->len, seq);
 437
 438         _proto("Rx DATA %%%u { #%u f=%02x }",
 439                sp->hdr.serial, seq, sp->hdr.flags);
 440
 441         state = READ_ONCE(call->state);
 442         if (state >= RXRPC_CALL_COMPLETE)
 443                 return;
 444
 445         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 446                 unsigned long timo = READ_ONCE(call->next_req_timo);
 447                 unsigned long now, expect_req_by;
 448
 449                 if (timo) {
 450                         now = jiffies;
 451                         expect_req_by = now + timo;
 452                         WRITE_ONCE(call->expect_req_by, expect_req_by);
 453                         rxrpc_reduce_call_timer(call, expect_req_by, now,
 454                                                 rxrpc_timer_set_for_idle);
 455                 }
 456         }
 457
 458         spin_lock(&call->input_lock);
 459
 460         /* Received data implicitly ACKs all of the request packets we sent
 461          * when we're acting as a client.
 462          */
 463         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 464              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 465             !rxrpc_receiving_reply(call))
 466                 goto unlock;
 467
 468         call->ackr_prev_seq = seq;
 469
 470         hard_ack = READ_ONCE(call->rx_hard_ack);
 471         if (after(seq, hard_ack + call->rx_winsize)) {
 472                 ack = RXRPC_ACK_EXCEEDS_WINDOW;
 473                 ack_serial = serial;
 474                 goto ack;
 475         }
 476
 477         flags = sp->hdr.flags;
 478         if (flags & RXRPC_JUMBO_PACKET) {
 479                 if (call->nr_jumbo_bad > 3) {
 480                         ack = RXRPC_ACK_NOSPACE;
 481                         ack_serial = serial;
 482                         goto ack;
 483                 }
 484                 annotation = 1;
 485         }
 486
 487 next_subpacket:
 488         queued = false;
 489         ix = seq & RXRPC_RXTX_BUFF_MASK;
 490         len = skb->len;
 491         if (flags & RXRPC_JUMBO_PACKET)
 492                 len = RXRPC_JUMBO_DATALEN;
 493
 494         if (flags & RXRPC_LAST_PACKET) {
 495                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 496                     seq != call->rx_top) {
 497                         rxrpc_proto_abort("LSN", call, seq);
 498                         goto unlock;
 499                 }
 500         } else {
 501                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 502                     after_eq(seq, call->rx_top)) {
 503                         rxrpc_proto_abort("LSA", call, seq);
 504                         goto unlock;
 505                 }
 506         }
 507
 508         trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 509         if (before_eq(seq, hard_ack)) {
 510                 ack = RXRPC_ACK_DUPLICATE;
 511                 ack_serial = serial;
 512                 goto skip;
 513         }
 514
 515         if (flags & RXRPC_REQUEST_ACK && !ack) {
 516                 ack = RXRPC_ACK_REQUESTED;
 517                 ack_serial = serial;
 518         }
 519
 520         if (call->rxtx_buffer[ix]) {
 521                 rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
 522                 if (ack != RXRPC_ACK_DUPLICATE) {
 523                         ack = RXRPC_ACK_DUPLICATE;
 524                         ack_serial = serial;
 525                 }
 526                 immediate_ack = true;
 527                 goto skip;
 528         }
 529
 530         /* Queue the packet.  We use a couple of memory barriers here as need
 531          * to make sure that rx_top is perceived to be set after the buffer
 532          * pointer and that the buffer pointer is set after the annotation and
 533          * the skb data.
 534          *
 535          * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 536          * and also rxrpc_fill_out_ack().
 537          */
 538         rxrpc_get_skb(skb, rxrpc_skb_rx_got);
 539         call->rxtx_annotations[ix] = annotation;
 540         smp_wmb();
 541         call->rxtx_buffer[ix] = skb;
 542         if (after(seq, call->rx_top)) {
 543                 smp_store_release(&call->rx_top, seq);
 544         } else if (before(seq, call->rx_top)) {
 545                 /* Send an immediate ACK if we fill in a hole */
 546                 if (!ack) {
 547                         ack = RXRPC_ACK_DELAY;
 548                         ack_serial = serial;
 549                 }
 550                 immediate_ack = true;
 551         }
 552         if (flags & RXRPC_LAST_PACKET) {
 553                 set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 554                 trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 555         } else {
 556                 trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 557         }
 558         queued = true;
 559
 560         if (after_eq(seq, call->rx_expect_next)) {
 561                 if (after(seq, call->rx_expect_next)) {
 562                         _net("OOS %u > %u", seq, call->rx_expect_next);
 563                         ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 564                         ack_serial = serial;
 565                 }
 566                 call->rx_expect_next = seq + 1;
 567         }
 568
 569 skip:
 570         offset += len;
 571         if (flags & RXRPC_JUMBO_PACKET) {
 572                 if (skb_copy_bits(skb, offset, &flags, 1) < 0) {
 573                         rxrpc_proto_abort("XJF", call, seq);
 574                         goto unlock;
 575                 }
 576                 offset += sizeof(struct rxrpc_jumbo_header);
 577                 seq++;
 578                 serial++;
 579                 annotation++;
 580                 if (flags & RXRPC_JUMBO_PACKET)
 581                         annotation |= RXRPC_RX_ANNO_JLAST;
 582                 if (after(seq, hard_ack + call->rx_winsize)) {
 583                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 584                         ack_serial = serial;
 585                         if (!jumbo_bad) {
 586                                 call->nr_jumbo_bad++;
 587                                 jumbo_bad = true;
 588                         }
 589                         goto ack;
 590                 }
 591
 592                 _proto("Rx DATA Jumbo %%%u", serial);
 593                 goto next_subpacket;
 594         }
 595
 596         if (queued && flags & RXRPC_LAST_PACKET && !ack) {
 597                 ack = RXRPC_ACK_DELAY;
 598                 ack_serial = serial;
 599         }
 600
 601 ack:
 602         if (ack)
 603                 rxrpc_propose_ACK(call, ack, skew, ack_serial,
 604                                   immediate_ack, true,
 605                                   rxrpc_propose_ack_input_data);
 606         else
 607                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, skew, serial,
 608                                   false, true,
 609                                   rxrpc_propose_ack_input_data);
 610
 611         if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1) {
 612                 trace_rxrpc_notify_socket(call->debug_id, serial);
 613                 rxrpc_notify_socket(call);
 614         }
 615
 616 unlock:
 617         spin_unlock(&call->input_lock);
 618         _leave(" [queued]");
 619 }
 620
 621 /*
 622  * Process a requested ACK.
 623  */
 624 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 625                                       ktime_t resp_time,
 626                                       rxrpc_serial_t orig_serial,
 627                                       rxrpc_serial_t ack_serial)
 628 {
 629         struct rxrpc_skb_priv *sp;
 630         struct sk_buff *skb;
 631         ktime_t sent_at;
 632         int ix;
 633
 634         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 635                 skb = call->rxtx_buffer[ix];
 636                 if (!skb)
 637                         continue;
 638
 639                 sent_at = skb->tstamp;
 640                 smp_rmb(); /* Read timestamp before serial. */
 641                 sp = rxrpc_skb(skb);
 642                 if (sp->hdr.serial != orig_serial)
 643                         continue;
 644                 goto found;
 645         }
 646
 647         return;
 648
 649 found:
 650         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 651                            orig_serial, ack_serial, sent_at, resp_time);
 652 }
 653
 654 /*
 655  * Process the response to a ping that we sent to find out if we lost an ACK.
 656  *
 657  * If we got back a ping response that indicates a lower tx_top than what we
 658  * had at the time of the ping transmission, we adjudge all the DATA packets
 659  * sent between the response tx_top and the ping-time tx_top to have been lost.
 660  */
 661 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 662 {
 663         rxrpc_seq_t top, bottom, seq;
 664         bool resend = false;
 665
 666         spin_lock_bh(&call->lock);
 667
 668         bottom = call->tx_hard_ack + 1;
 669         top = call->acks_lost_top;
 670         if (before(bottom, top)) {
 671                 for (seq = bottom; before_eq(seq, top); seq++) {
 672                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 673                         u8 annotation = call->rxtx_annotations[ix];
 674                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 675
 676                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 677                                 continue;
 678                         annotation &= ~RXRPC_TX_ANNO_MASK;
 679                         annotation |= RXRPC_TX_ANNO_RETRANS;
 680                         call->rxtx_annotations[ix] = annotation;
 681                         resend = true;
 682                 }
 683         }
 684
 685         spin_unlock_bh(&call->lock);
 686
 687         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 688                 rxrpc_queue_call(call);
 689 }
 690
 691 /*
 692  * Process a ping response.
 693  */
 694 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 695                                       ktime_t resp_time,
 696                                       rxrpc_serial_t orig_serial,
 697                                       rxrpc_serial_t ack_serial)
 698 {
 699         rxrpc_serial_t ping_serial;
 700         ktime_t ping_time;
 701
 702         ping_time = call->ping_time;
 703         smp_rmb();
 704         ping_serial = READ_ONCE(call->ping_serial);
 705
 706         if (orig_serial == call->acks_lost_ping)
 707                 rxrpc_input_check_for_lost_ack(call);
 708
 709         if (before(orig_serial, ping_serial) ||
 710             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 711                 return;
 712         if (after(orig_serial, ping_serial))
 713                 return;
 714
 715         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 716                            orig_serial, ack_serial, ping_time, resp_time);
 717 }
 718
 719 /*
 720  * Process the extra information that may be appended to an ACK packet
 721  */
 722 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 723                                 struct rxrpc_ackinfo *ackinfo)
 724 {
 725         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 726         struct rxrpc_peer *peer;
 727         unsigned int mtu;
 728         bool wake = false;
 729         u32 rwind = ntohl(ackinfo->rwind);
 730
 731         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 732                sp->hdr.serial,
 733                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 734                rwind, ntohl(ackinfo->jumbo_max));
 735
 736         if (call->tx_winsize != rwind) {
 737                 if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 738                         rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 739                 if (rwind > call->tx_winsize)
 740                         wake = true;
 741                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
 742                                             ntohl(ackinfo->rwind), wake);
 743                 call->tx_winsize = rwind;
 744         }
 745
 746         if (call->cong_ssthresh > rwind)
 747                 call->cong_ssthresh = rwind;
 748
 749         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 750
 751         peer = call->peer;
 752         if (mtu < peer->maxdata) {
 753                 spin_lock_bh(&peer->lock);
 754                 peer->maxdata = mtu;
 755                 peer->mtu = mtu + peer->hdrsize;
 756                 spin_unlock_bh(&peer->lock);
 757                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 758         }
 759
 760         if (wake)
 761                 wake_up(&call->waitq);
 762 }
 763
 764 /*
 765  * Process individual soft ACKs.
 766  *
 767  * Each ACK in the array corresponds to one packet and can be either an ACK or
 768  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 769  * packets that lie beyond the end of the ACK list are scheduled for resend by
 770  * the timer on the basis that the peer might just not have processed them at
 771  * the time the ACK was sent.
 772  */
 773 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 774                                   rxrpc_seq_t seq, int nr_acks,
 775                                   struct rxrpc_ack_summary *summary)
 776 {
 777         int ix;
 778         u8 annotation, anno_type;
 779
 780         for (; nr_acks > 0; nr_acks--, seq++) {
 781                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 782                 annotation = call->rxtx_annotations[ix];
 783                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 784                 annotation &= ~RXRPC_TX_ANNO_MASK;
 785                 switch (*acks++) {
 786                 case RXRPC_ACK_TYPE_ACK:
 787                         summary->nr_acks++;
 788                         if (anno_type == RXRPC_TX_ANNO_ACK)
 789                                 continue;
 790                         summary->nr_new_acks++;
 791                         call->rxtx_annotations[ix] =
 792                                 RXRPC_TX_ANNO_ACK | annotation;
 793                         break;
 794                 case RXRPC_ACK_TYPE_NACK:
 795                         if (!summary->nr_nacks &&
 796                             call->acks_lowest_nak != seq) {
 797                                 call->acks_lowest_nak = seq;
 798                                 summary->new_low_nack = true;
 799                         }
 800                         summary->nr_nacks++;
 801                         if (anno_type == RXRPC_TX_ANNO_NAK)
 802                                 continue;
 803                         summary->nr_new_nacks++;
 804                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 805                                 continue;
 806                         call->rxtx_annotations[ix] =
 807                                 RXRPC_TX_ANNO_NAK | annotation;
 808                         break;
 809                 default:
 810                         return rxrpc_proto_abort("SFT", call, 0);
 811                 }
 812         }
 813 }
 814
 815 /*
 816  * Process an ACK packet.
 817  *
 818  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 819  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 820  *
 821  * A hard-ACK means that a packet has been processed and may be discarded; a
 822  * soft-ACK means that the packet may be discarded and retransmission
 823  * requested.  A phase is complete when all packets are hard-ACK'd.
 824  */
 825 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
 826                             u16 skew)
 827 {
 828         struct rxrpc_ack_summary summary = { 0 };
 829         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 830         union {
 831                 struct rxrpc_ackpacket ack;
 832                 struct rxrpc_ackinfo info;
 833                 u8 acks[RXRPC_MAXACKS];
 834         } buf;
 835         rxrpc_serial_t acked_serial;
 836         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 837         int nr_acks, offset, ioffset;
 838
 839         _enter("");
 840
 841         offset = sizeof(struct rxrpc_wire_header);
 842         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 843                 _debug("extraction failure");
 844                 return rxrpc_proto_abort("XAK", call, 0);
 845         }
 846         offset += sizeof(buf.ack);
 847
 848         acked_serial = ntohl(buf.ack.serial);
 849         first_soft_ack = ntohl(buf.ack.firstPacket);
 850         prev_pkt = ntohl(buf.ack.previousPacket);
 851         hard_ack = first_soft_ack - 1;
 852         nr_acks = buf.ack.nAcks;
 853         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 854                               buf.ack.reason : RXRPC_ACK__INVALID);
 855
 856         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 857                            first_soft_ack, prev_pkt,
 858                            summary.ack_reason, nr_acks);
 859
 860         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 861                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 862                                           sp->hdr.serial);
 863         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 864                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 865                                           sp->hdr.serial);
 866
 867         if (buf.ack.reason == RXRPC_ACK_PING) {
 868                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 869                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 870                                   skew, sp->hdr.serial, true, true,
 871                                   rxrpc_propose_ack_respond_to_ping);
 872         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 873                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 874                                   skew, sp->hdr.serial, true, true,
 875                                   rxrpc_propose_ack_respond_to_ack);
 876         }
 877
 878         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 879         if (before(first_soft_ack, call->ackr_first_seq) ||
 880             before(prev_pkt, call->ackr_prev_seq))
 881                 return;
 882
 883         buf.info.rxMTU = 0;
 884         ioffset = offset + nr_acks + 3;
 885         if (skb->len >= ioffset + sizeof(buf.info) &&
 886             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 887                 return rxrpc_proto_abort("XAI", call, 0);
 888
 889         spin_lock(&call->input_lock);
 890
 891         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 892         if (before(first_soft_ack, call->ackr_first_seq) ||
 893             before(prev_pkt, call->ackr_prev_seq))
 894                 goto out;
 895         call->acks_latest_ts = skb->tstamp;
 896         call->acks_latest = sp->hdr.serial;
 897
 898         call->ackr_first_seq = first_soft_ack;
 899         call->ackr_prev_seq = prev_pkt;
 900
 901         /* Parse rwind and mtu sizes if provided. */
 902         if (buf.info.rxMTU)
 903                 rxrpc_input_ackinfo(call, skb, &buf.info);
 904
 905         if (first_soft_ack == 0) {
 906                 rxrpc_proto_abort("AK0", call, 0);
 907                 goto out;
 908         }
 909
 910         /* Ignore ACKs unless we are or have just been transmitting. */
 911         switch (READ_ONCE(call->state)) {
 912         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 913         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 914         case RXRPC_CALL_SERVER_SEND_REPLY:
 915         case RXRPC_CALL_SERVER_AWAIT_ACK:
 916                 break;
 917         default:
 918                 goto out;
 919         }
 920
 921         if (before(hard_ack, call->tx_hard_ack) ||
 922             after(hard_ack, call->tx_top)) {
 923                 rxrpc_proto_abort("AKW", call, 0);
 924                 goto out;
 925         }
 926         if (nr_acks > call->tx_top - hard_ack) {
 927                 rxrpc_proto_abort("AKN", call, 0);
 928                 goto out;
 929         }
 930
 931         if (after(hard_ack, call->tx_hard_ack)) {
 932                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 933                         rxrpc_end_tx_phase(call, false, "ETA");
 934                         goto out;
 935                 }
 936         }
 937
 938         if (nr_acks > 0) {
 939                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 940                         rxrpc_proto_abort("XSA", call, 0);
 941                         goto out;
 942                 }
 943                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 944                                       &summary);
 945         }
 946
 947         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 948             RXRPC_TX_ANNO_LAST &&
 949             summary.nr_acks == call->tx_top - hard_ack &&
 950             rxrpc_is_client_call(call))
 951                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 952                                   false, true,
 953                                   rxrpc_propose_ack_ping_for_lost_reply);
 954
 955         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 956 out:
 957         spin_unlock(&call->input_lock);
 958 }
 959
 960 /*
 961  * Process an ACKALL packet.
 962  */
 963 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 964 {
 965         struct rxrpc_ack_summary summary = { 0 };
 966         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 967
 968         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 969
 970         spin_lock(&call->input_lock);
 971
 972         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 973                 rxrpc_end_tx_phase(call, false, "ETL");
 974
 975         spin_unlock(&call->input_lock);
 976 }
 977
 978 /*
 979  * Process an ABORT packet directed at a call.
 980  */
 981 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 982 {
 983         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 984         __be32 wtmp;
 985         u32 abort_code = RX_CALL_DEAD;
 986
 987         _enter("");
 988
 989         if (skb->len >= 4 &&
 990             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 991                           &wtmp, sizeof(wtmp)) >= 0)
 992                 abort_code = ntohl(wtmp);
 993
 994         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
 995
 996         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
 997
 998         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 999                                       abort_code, -ECONNABORTED))
1000                 rxrpc_notify_socket(call);
1001 }
1002
1003 /*
1004  * Process an incoming call packet.
1005  */
1006 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1007                                     struct sk_buff *skb, u16 skew)
1008 {
1009         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1010         unsigned long timo;
1011
1012         _enter("%p,%p", call, skb);
1013
1014         timo = READ_ONCE(call->next_rx_timo);
1015         if (timo) {
1016                 unsigned long now = jiffies, expect_rx_by;
1017
1018                 expect_rx_by = now + timo;
1019                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1020                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1021                                         rxrpc_timer_set_for_normal);
1022         }
1023
1024         switch (sp->hdr.type) {
1025         case RXRPC_PACKET_TYPE_DATA:
1026                 rxrpc_input_data(call, skb, skew);
1027                 break;
1028
1029         case RXRPC_PACKET_TYPE_ACK:
1030                 rxrpc_input_ack(call, skb, skew);
1031                 break;
1032
1033         case RXRPC_PACKET_TYPE_BUSY:
1034                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1035
1036                 /* Just ignore BUSY packets from the server; the retry and
1037                  * lifespan timers will take care of business.  BUSY packets
1038                  * from the client don't make sense.
1039                  */
1040                 break;
1041
1042         case RXRPC_PACKET_TYPE_ABORT:
1043                 rxrpc_input_abort(call, skb);
1044                 break;
1045
1046         case RXRPC_PACKET_TYPE_ACKALL:
1047                 rxrpc_input_ackall(call, skb);
1048                 break;
1049
1050         default:
1051                 break;
1052         }
1053
1054         _leave("");
1055 }
1056
1057 /*
1058  * Handle a new service call on a channel implicitly completing the preceding
1059  * call on that channel.  This does not apply to client conns.
1060  *
1061  * TODO: If callNumber > call_id + 1, renegotiate security.
1062  */
1063 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1064                                           struct rxrpc_connection *conn,
1065                                           struct rxrpc_call *call)
1066 {
1067         switch (READ_ONCE(call->state)) {
1068         case RXRPC_CALL_SERVER_AWAIT_ACK:
1069                 rxrpc_call_completed(call);
1070                 /* Fall through */
1071         case RXRPC_CALL_COMPLETE:
1072                 break;
1073         default:
1074                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1075                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1076                         rxrpc_queue_call(call);
1077                 }
1078                 trace_rxrpc_improper_term(call);
1079                 break;
1080         }
1081
1082         spin_lock(&rx->incoming_lock);
1083         __rxrpc_disconnect_call(conn, call);
1084         spin_unlock(&rx->incoming_lock);
1085         rxrpc_notify_socket(call);
1086 }
1087
1088 /*
1089  * post connection-level events to the connection
1090  * - this includes challenges, responses, some aborts and call terminal packet
1091  *   retransmission.
1092  */
1093 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1094                                       struct sk_buff *skb)
1095 {
1096         _enter("%p,%p", conn, skb);
1097
1098         skb_queue_tail(&conn->rx_queue, skb);
1099         rxrpc_queue_conn(conn);
1100 }
1101
1102 /*
1103  * post endpoint-level events to the local endpoint
1104  * - this includes debug and version messages
1105  */
1106 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1107                                        struct sk_buff *skb)
1108 {
1109         _enter("%p,%p", local, skb);
1110
1111         skb_queue_tail(&local->event_queue, skb);
1112         rxrpc_queue_local(local);
1113 }
1114
1115 /*
1116  * put a packet up for transport-level abort
1117  */
1118 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1119 {
1120         CHECK_SLAB_OKAY(&local->usage);
1121
1122         skb_queue_tail(&local->reject_queue, skb);
1123         rxrpc_queue_local(local);
1124 }
1125
1126 /*
1127  * Extract the wire header from a packet and translate the byte order.
1128  */
1129 static noinline
1130 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1131 {
1132         struct rxrpc_wire_header whdr;
1133
1134         /* dig out the RxRPC connection details */
1135         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1136                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1137                                       tracepoint_string("bad_hdr"));
1138                 return -EBADMSG;
1139         }
1140
1141         memset(sp, 0, sizeof(*sp));
1142         sp->hdr.epoch           = ntohl(whdr.epoch);
1143         sp->hdr.cid             = ntohl(whdr.cid);
1144         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1145         sp->hdr.seq             = ntohl(whdr.seq);
1146         sp->hdr.serial          = ntohl(whdr.serial);
1147         sp->hdr.flags           = whdr.flags;
1148         sp->hdr.type            = whdr.type;
1149         sp->hdr.userStatus      = whdr.userStatus;
1150         sp->hdr.securityIndex   = whdr.securityIndex;
1151         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1152         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1153         return 0;
1154 }
1155
1156 /*
1157  * handle data received on the local endpoint
1158  * - may be called in interrupt context
1159  *
1160  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1161  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1162  * being cleared in the middle of processing this function.
1163  *
1164  * Called with the RCU read lock held from the IP layer via UDP.
1165  */
1166 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1167 {
1168         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1169         struct rxrpc_connection *conn;
1170         struct rxrpc_channel *chan;
1171         struct rxrpc_call *call = NULL;
1172         struct rxrpc_skb_priv *sp;
1173         struct rxrpc_peer *peer = NULL;
1174         struct rxrpc_sock *rx = NULL;
1175         unsigned int channel;
1176         int skew = 0;
1177
1178         _enter("%p", udp_sk);
1179
1180         if (unlikely(!local)) {
1181                 kfree_skb(skb);
1182                 return 0;
1183         }
1184         if (skb->tstamp == 0)
1185                 skb->tstamp = ktime_get_real();
1186
1187         rxrpc_new_skb(skb, rxrpc_skb_rx_received);
1188
1189         skb_pull(skb, sizeof(struct udphdr));
1190
1191         /* The UDP protocol already released all skb resources;
1192          * we are free to add our own data there.
1193          */
1194         sp = rxrpc_skb(skb);
1195
1196         /* dig out the RxRPC connection details */
1197         if (rxrpc_extract_header(sp, skb) < 0)
1198                 goto bad_message;
1199
1200         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1201                 static int lose;
1202                 if ((lose++ & 7) == 7) {
1203                         trace_rxrpc_rx_lose(sp);
1204                         rxrpc_free_skb(skb, rxrpc_skb_rx_lost);
1205                         return 0;
1206                 }
1207         }
1208
1209         if (skb->tstamp == 0)
1210                 skb->tstamp = ktime_get_real();
1211         trace_rxrpc_rx_packet(sp);
1212
1213         switch (sp->hdr.type) {
1214         case RXRPC_PACKET_TYPE_VERSION:
1215                 if (rxrpc_to_client(sp))
1216                         goto discard;
1217                 rxrpc_post_packet_to_local(local, skb);
1218                 goto out;
1219
1220         case RXRPC_PACKET_TYPE_BUSY:
1221                 if (rxrpc_to_server(sp))
1222                         goto discard;
1223                 /* Fall through */
1224         case RXRPC_PACKET_TYPE_ACK:
1225         case RXRPC_PACKET_TYPE_ACKALL:
1226                 if (sp->hdr.callNumber == 0)
1227                         goto bad_message;
1228                 /* Fall through */
1229         case RXRPC_PACKET_TYPE_ABORT:
1230                 break;
1231
1232         case RXRPC_PACKET_TYPE_DATA:
1233                 if (sp->hdr.callNumber == 0 ||
1234                     sp->hdr.seq == 0)
1235                         goto bad_message;
1236                 if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
1237                     !rxrpc_validate_jumbo(skb))
1238                         goto bad_message;
1239                 break;
1240
1241         case RXRPC_PACKET_TYPE_CHALLENGE:
1242                 if (rxrpc_to_server(sp))
1243                         goto discard;
1244                 break;
1245         case RXRPC_PACKET_TYPE_RESPONSE:
1246                 if (rxrpc_to_client(sp))
1247                         goto discard;
1248                 break;
1249
1250                 /* Packet types 9-11 should just be ignored. */
1251         case RXRPC_PACKET_TYPE_PARAMS:
1252         case RXRPC_PACKET_TYPE_10:
1253         case RXRPC_PACKET_TYPE_11:
1254                 goto discard;
1255
1256         default:
1257                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1258                 goto bad_message;
1259         }
1260
1261         if (sp->hdr.serviceId == 0)
1262                 goto bad_message;
1263
1264         if (rxrpc_to_server(sp)) {
1265                 /* Weed out packets to services we're not offering.  Packets
1266                  * that would begin a call are explicitly rejected and the rest
1267                  * are just discarded.
1268                  */
1269                 rx = rcu_dereference(local->service);
1270                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1271                             sp->hdr.serviceId != rx->second_service)) {
1272                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1273                             sp->hdr.seq == 1)
1274                                 goto unsupported_service;
1275                         goto discard;
1276                 }
1277         }
1278
1279         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1280         if (conn) {
1281                 if (sp->hdr.securityIndex != conn->security_ix)
1282                         goto wrong_security;
1283
1284                 if (sp->hdr.serviceId != conn->service_id) {
1285                         int old_id;
1286
1287                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1288                                 goto reupgrade;
1289                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1290                                          sp->hdr.serviceId);
1291
1292                         if (old_id != conn->params.service_id &&
1293                             old_id != sp->hdr.serviceId)
1294                                 goto reupgrade;
1295                 }
1296
1297                 if (sp->hdr.callNumber == 0) {
1298                         /* Connection-level packet */
1299                         _debug("CONN %p {%d}", conn, conn->debug_id);
1300                         rxrpc_post_packet_to_conn(conn, skb);
1301                         goto out;
1302                 }
1303
1304                 /* Note the serial number skew here */
1305                 skew = (int)sp->hdr.serial - (int)conn->hi_serial;
1306                 if (skew >= 0) {
1307                         if (skew > 0)
1308                                 conn->hi_serial = sp->hdr.serial;
1309                 } else {
1310                         skew = -skew;
1311                         skew = min(skew, 65535);
1312                 }
1313
1314                 /* Call-bound packets are routed by connection channel. */
1315                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1316                 chan = &conn->channels[channel];
1317
1318                 /* Ignore really old calls */
1319                 if (sp->hdr.callNumber < chan->last_call)
1320                         goto discard;
1321
1322                 if (sp->hdr.callNumber == chan->last_call) {
1323                         if (chan->call ||
1324                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1325                                 goto discard;
1326
1327                         /* For the previous service call, if completed
1328                          * successfully, we discard all further packets.
1329                          */
1330                         if (rxrpc_conn_is_service(conn) &&
1331                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1332                                 goto discard;
1333
1334                         /* But otherwise we need to retransmit the final packet
1335                          * from data cached in the connection record.
1336                          */
1337                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1338                                 trace_rxrpc_rx_data(chan->call_debug_id,
1339                                                     sp->hdr.seq,
1340                                                     sp->hdr.serial,
1341                                                     sp->hdr.flags, 0);
1342                         rxrpc_post_packet_to_conn(conn, skb);
1343                         goto out;
1344                 }
1345
1346                 call = rcu_dereference(chan->call);
1347
1348                 if (sp->hdr.callNumber > chan->call_id) {
1349                         if (rxrpc_to_client(sp))
1350                                 goto reject_packet;
1351                         if (call)
1352                                 rxrpc_input_implicit_end_call(rx, conn, call);
1353                         call = NULL;
1354                 }
1355
1356                 if (call) {
1357                         if (sp->hdr.serviceId != call->service_id)
1358                                 call->service_id = sp->hdr.serviceId;
1359                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1360                                 call->rx_serial = sp->hdr.serial;
1361                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1362                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1363                 }
1364         }
1365
1366         if (!call || atomic_read(&call->usage) == 0) {
1367                 if (rxrpc_to_client(sp) ||
1368                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1369                         goto bad_message;
1370                 if (sp->hdr.seq != 1)
1371                         goto discard;
1372                 call = rxrpc_new_incoming_call(local, rx, skb);
1373                 if (!call)
1374                         goto reject_packet;
1375                 rxrpc_send_ping(call, skb, skew);
1376                 mutex_unlock(&call->user_mutex);
1377         }
1378
1379         rxrpc_input_call_packet(call, skb, skew);
1380         goto discard;
1381
1382 discard:
1383         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1384 out:
1385         trace_rxrpc_rx_done(0, 0);
1386         return 0;
1387
1388 wrong_security:
1389         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1390                           RXKADINCONSISTENCY, EBADMSG);
1391         skb->priority = RXKADINCONSISTENCY;
1392         goto post_abort;
1393
1394 unsupported_service:
1395         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1396                           RX_INVALID_OPERATION, EOPNOTSUPP);
1397         skb->priority = RX_INVALID_OPERATION;
1398         goto post_abort;
1399
1400 reupgrade:
1401         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1402                           RX_PROTOCOL_ERROR, EBADMSG);
1403         goto protocol_error;
1404
1405 bad_message:
1406         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1407                           RX_PROTOCOL_ERROR, EBADMSG);
1408 protocol_error:
1409         skb->priority = RX_PROTOCOL_ERROR;
1410 post_abort:
1411         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1412 reject_packet:
1413         trace_rxrpc_rx_done(skb->mark, skb->priority);
1414         rxrpc_reject_packet(local, skb);
1415         _leave(" [badmsg]");
1416         return 0;
1417 }